FORT COLLINS, Colo. — A storage tank damaged by floodwaters dumped 7,500 gallons of crude oil into the Poudre River near Windsor in northern Colorado, slickening vegetation a quarter-mile downstream, but apparently not affecting any drinking water, state officials said Friday.

The bank where the storage tank sat next to the river was undercut by the high spring river flows, causing it to drop and break a valve, Todd Hartman of the Colorado Department of Natural Resources said in a statement.

The tank released all of its contents, which was 178 barrels of crude oil, or roughly 7,500 gallons, Hartman said. A second tank nearby appeared to be unaffected.

The tank's operator, Noble Energy Inc., discovered the spill Friday and reported it to state officials. Colorado Oiland Gas Conservation Commission officials and state Department of Public Health and Environment water quality staff responded, along with a Noble Energy response team, Hartman said.

Cleanup crews deployed absorbent material where oil could be seen, while a vacuum truck removed oily water from a low-lying area near the tank.

Calls and an email to Noble Energy after office hours Friday were not immediately returned.

The site of the spill is southeast of Fort Collins near the Poudre River Trail.